Electrical properties of Bi-implanted amorphous chalcogenide films

TL;DR

This study explores how bismuth ion implantation enhances the electrical conductivity and modifies the thermoelectric properties of amorphous chalcogenide films, revealing defect-related mechanisms behind the conductivity increase.

Contribution

It demonstrates that Bi implantation deactivates native defects and creates electrically active defects, leading to significantly improved conductivity in amorphous chalcogenide films.

Findings

Bi implantation increases film conductivity

Negative Seebeck coefficient indicates electron conduction

Defect analysis shows creation of electrically active defects

Abstract

The impact of Bi implantation on the conductivity and the thermopower of amorphous chalcogenide films is investigated. Incorporation of Bi in Ge-Sb-Te and GeTe results in enhanced conductivity. The negative Seebeck coefficient confirms onset of the electron conductivity in GeTe implanted with Bi at a dose of 2x1016 cm-2. The enhanced conductivity is accompanied by defect accumulation in the films upon implantation as is inferred by using analysis of the space-charge limited current. The results indicate that native coordination defects in lone-pair semiconductors can be deactivated by means of ion implantation, and higher conductivity of the films stems from additional electrically active defects created by implantation of bismuth.